Large transport aircraft, both military and commercial, typically include a main landing gear arrangement that supports most of the aircraft weight, along with a nose gear for stability and steering. The main landing gear usually includes at least two posts, each of which carries a truck. Each truck carries multiple wheels, and each wheel includes one or more brakes. Larger aircraft typically include a left main gear, a right main gear, and one or more intermediate main gears between the left and right gears. The wheels of the left and right gears include brakes, and in some cases, the wheels of the intermediate gears also include brakes. For example, the MD-11 aircraft includes a single intermediate post with wheels having brakes that are mechanically linked to the brakes of the left and right posts. The wheels of the intermediate gear can be braked at a level between that applied to the left post wheels and that applied to the right post wheels. The nose gear is typically unbraked, so as not to interfere with aircraft steering, and because the nose gear carries only a small fraction of the aircraft weight.
The stopping distance of an aircraft depends primarily on aircraft weight and braking effectiveness. As transport aircraft increase in size, there has been continual pressure on manufacturers to increase braking effectiveness. While the current systems described above are adequate for braking current aircraft, it may be desirable to further increase braking effectiveness, both for current generation aircraft and larger, next generation aircraft. Furthermore, it may be desirable to reduce the turning radius of aircraft, so as to allow the aircraft to use smaller and/or more crowded airport spaces.